1. Field of the Invention
The present invention relates to an information device such as a cellular phone unit, a personal digital assistance and a personal computer, in particular, to an information device having a function for displaying a picture.
2. Description of the Related Art
Nowadays, mobile communication terminal units such as cellular phone units and simplified cellular phone units for use in mobile communication can transmit and receive picture data and display pictures. In the third generation mobile communication, the data communication rate is so high that picture data and so forth that have a large file size can be transmitted and received. Thus, third generation mobile communication terminal units can transmit and receive picture data having a much larger size in pixel than the current mobile communication terminal units can, although not reaching the ability of personal computers. Consequently, it can be expected that the third generation mobile communication terminal units will process picture data having large data sizes and display pictures having large size in pixel.
However, since cellular phone units and so forth are carried about by users, they should be small and light. Consequently, the sizes and resolutions of displays of the cellular phone units are restricted. Thus, it is difficult to display a picture having a large size in pixel at a time. To solve such a problem, normally, cellular phone units reduce the size of a picture of a large number of pixels or scroll a picture of a large number of pixels so as to display a part thereof at a time.
The reduced display is suitable for a user to grasp the whole picture. In contrast, the scroll display is suitable for a user to see the detail of a picture.
To reduce the size of a picture of a large number of pixels and display the reduced picture, a cellular phone unit or the like should perform a picture developing process, a picture reducing process corresponding to the number of dots and the resolution of the display, a picture drawing process, and so forth, and it takes a long time.